1. Field of Invention
The present invention relates to apparatus and method for motion estimation, used in video compression. More particularly, the present invention relates to apparatus and method for motion estimation, which is supporting multiple video compression standards.
2. Description of Related Art
Generally, the motion estimation is implemented by a manner, as shown in FIG. 1 about a motion estimation apparatus 100. The integer part estimator 101 receives the data 111 of original frames and the data 112 of reference frames, and performs a wide search for the integer part. Then, the decimal part estimator 102 performs a small search for the decimal part on the motion vectors with best results. The searching method is calculating a cost function value for each of the motion vectors, and comparing the cost function values to select the best one of the motion vectors and its corresponding block mode 113.
In different video compression standards, the block size available for use may be different, and the filter coefficient used for interpolating the decimal reference frame may be different, either. The conventional method takes a specific video compression standard with the block size and a specific interpolation filter to implement the motion estimation. This may cause that the same motion estimation mode cannot effectively support the coding in multiple standards. For example, the block size for the standard of H.264/AVC (Advanced Video Coding) can change from 16×16 to 4×4. The interpolation filter is the 6-tap Wiener filter. However, the block for the MPEG-4 (Motion Picture Expert Group-4) can only support 16×16 or 8×8, and the interpolation filter is the 2-tap Bilinear filter or the 8-tap Wiener filter. The motion estimation modes for above two designs with specific standards cannot be compatible to each other.
Even though the U.S. Pat. No. 5,920,353 proposes a multi-standard coder, it is just related to the function block belonging to the decoding loop of the coder. So far, the conventional technology still cannot provide the high-quality compressing function under condition of supporting the multiple video compression standard.